Scalp and Cranial Cavity

Question 1

What is the scalp?

Answer 1

The skin and subcutaneous tissue that covers the neurocranium from the superior nuchal line of the occipital bone to the supraorbital margins of the frontal bone
Laterally it extends over the temporal fascia to the zygomatic arch

Question 2

What is the face?

Answer 2

The anterior aspect of the head from forehead to chin and from one ear to the other

Question 3

What are the layers of the scalp?

Answer 3

Skin
Dense connective tissue
Epicranial aponeurosis
Loose connective tissue
Pericranium

Question 4

Describe the skin of the scalp

Answer 4

Outermost layer
Contains hair follicles, sweat and sebaceous glands, thickest over the occipital bone

Question 5

Describe the dense connective tissue of the scalp

Answer 5

Subcutaneous layer richly vascularised with cutaneous nerves

Question 6

Describe the epicranial aponeurosis of the scalp

Answer 6

Tendon and muscle of occipitofrontalis
Prevents superficial wounds from gaping open - when this layer is compromised (laceration) gaping wounds result that require sutures to close

Question 7

Describe the loose connective tissue of the scalp

Answer 7

Loose areolar tissue that allows free movement of outer layers over underlying calvaria
Contains spaces susceptible to distension with fluid or infection spread

Question 8

Describe the pericranium of the skull

Answer 8

External periosteum of the skull

Question 9

Why can fluid or infection spread to the eyelids or root of nose?

Answer 9

Between the aponeurosis and pericranium there are potential spaces for accumulation of fluid eg - blood
The frontal belly of the occipitofrontalis inserts into skin and subcutaneous tissue - not bone
Spread via emissary veins

Question 10

Which nerves nerves innervates the scalp?

Answer 10

C2,3
CN V (1,2 and 3)

Question 11

Which branches of CN Va innervate the scalp?

Answer 11

Supraorbital
Supratrochlear
Infratrochlear
External nasal
Lacrimal

Question 12

Which branches of CN Vb innervate the scalp?

Answer 12

Zygomaticotemporal
Zygomaticofacial
Infraorbital

Question 13

Which branches of CN Vc innervate the scalp?

Answer 13

Auriculotemporal
Buccal
Mental

Question 14

Which branches of C2 and 3 innervate the scalp?

Answer 14

C2 - greater occipital
C3 - third occipital
C2,3 - great auricular and lesser occipital

Question 15

What supplies the skin over the angle of the mandible?

Answer 15

Not CN V but by the cervical plexus with the great auricular nerve (C2 and 3)

Question 16

Describe blood supply and drainage of the scalp

Answer 16

Arterial supply is from both the internal (anterior scalp) and external (lateral and posterior scalp) carotid arteries
Veins run alongside the arteries and have the same names draining to the EJV with the exception of the occipital vein that drains to the IJV

Question 17

Which branches of the internal carotid artery and vein supply and drain the scalp?

Answer 17

Supraorbital
Supratrochlear

Question 18

Which branches of the external carotid artery and vein supply and drain the scalp

Answer 18

Superficial temporal
Posterior auricular
Occipital - (occipital vein drains to IJV)

Question 19

Why is profuse bleeding common in scalp lacerations?

Answer 19

Arterial anastomoses are prevalent in the scalp and these lie superficially

Question 20

Describe lymphatic drainage of the scalp?

Answer 20

Posterior - mastoid and occipital nodes drain to deep cervical nodes
Anterior - pre-auricular and parotid nodes

Question 21

Describe the anterior cranial fossa

Answer 21

Frontal ethmoid and sphenoid bones
Shallowest part of the cranial base
Occupied by the frontal lobes

Question 22

What role does CN I play in the anterior fossa?

Answer 22

Olfactory bulbs receive nerve fibres from the nasal cavity via the foramina of the cribriform plate (olfaction)

Question 23

How may cribiform plate fractures present?

Answer 23

With CSF rhinorrhoea

Question 24

Describe the middle cranial fossa

Answer 24

Sphenoid and temporal bones
Occupied by the temporal lobes

Question 25

Where is the pituitary gland found in the middle cranial fossa?

Answer 25

In the hypophyseal (pituitary) fossa - deepest part of the sella turcica

Question 26

What surrounds the pituitary gland?

Answer 26

4 clinoid processes and 2 superior projections - dorsum sellae posteriorly and tuberculum sellae anteriorly

Question 27

What foramina are found in the sphenoid bone?

Answer 27

Foramen rotundum - lateral Pterygoid canal - medial

Question 28

What are the main features of the sphenoid bone?

Answer 28

Greater wing Lesser wing Sphenoid sinus Superior orbital fissure Dorsum sellae Medial pterygoid plate Lateral pterygoid plate

Question 29

What is the space between the medial and lateral pterygoid plates called?

Answer 29

The pterygoid fossa

Question 30

Describe the posterior cranial fossa

Answer 30

Sphenoid, occipital and temporal bones Occupied by the cerebellum and brainstem

Question 31

What foramina are found in the posterior cranial fossa?

Answer 31

Foramen magnum Jugular foramen Hypoglossal canal

Question 32

What are granular foveolae?

Answer 32

Arachnoid granulations that return CSF to the venous circulation

Question 33

Describe the bone structure of the calvaria

Answer 33

Pericranium External table Diploë (compact bone) Internal table Dura

Question 34

What are buttresses?

Answer 34

Thicker portions of cranial bone (pillars) that transmit forces around weaker regions of the cranium (bypassing orbits and nasal cavity)

Question 35

Describe the frontonasal buttress

Answer 35

From the region of the canine teeth between the nasal and the orbital cavities to the central frontal bone

Question 36

Describe the zygomatic arch-lateral orbital margin buttress

Question 37

Describe the occipital buttresses

Answer 37

Transmit forces received lateral to the foramen magnum from the vertebral column

Question 38

Name the different buttresses

Answer 38

Frontosagittal buttress Frontonasal buttress Zygomatic arch-lateral orbital margin buttress Occipital buttress

Question 39

What are cranial meninges?

Answer 39

Membranous layers that help in protection of the brain

Question 40

Name the different cranial meninges

Answer 40

Dura mater Arachnoid mater Subarachnoid space Pia mater

Question 41

Describe the layers of the dura mater

Answer 41

Periosteal layer - attached to bone Meningeal layer - in contact with arachnoid mater These two layers separate at venous sinuses and dura folds

Question 42

Describe the arachnoid mater

Answer 42

Lines the dura mater Trabeculae project from internal surface, across the subarachnoid space and are continuous with the pia mater

Question 43

Describe the subarachnoid space

Answer 43

Contains CSF and blood vessels Arachnoid villi reabsorb CSF into the venous system

Question 44

What are arachnoid granulations and where are they found?

Answer 44

Collections of arachnoid villi found in the sagittal sinus and lateral lacunae

Question 45

Describe the pia mater

Answer 45

Thin membrane attached to the surface of the brain As it adheres to the brain surface, it enters the sulci of the brain

Question 46

What do dura mater folds do?

Answer 46

The limit the movement of the brain within the cavity

Question 47

Name the dura mater folds

Answer 47

Falx Cerebri Tentrorium cerebelli Falx Cerebelli Diaphragma Sellae

Question 48

What supplies the dura mater and calvaria?

Answer 48

Meningeal arteries in the periosteal layer: Anterior meningeal arteries Middle and Accessory meningeal arteries Posterior meningeal arteries